Despite recent major advances in leukemia research the pathobiology of chronic

Published December 26, 2016

Despite recent major advances in leukemia research the pathobiology of chronic lymphocytic leukemia (CLL) remains poorly understood. glucocorticoids and non-steroidal anti-inflammatory possess anti-tumor activity and glucocorticoids have been broadly used to treat CLL and its complications. Recent clinical trials exhibited that tyrosine kinase inhibitors such as ibrutinib and the immune-modulatory agent lenalidomide induced impressive clinical responses in CLL patients with relapsed or refractory disease. As those pro-inflammatory pathway inhibitors and immune modulating drugs proved to be effective in CLL other agents with comparable activities are currently investigated in clinical trials. New insights into the pathobiology of CLL and the development of novel classes of drugs will undoubtedly provide us with effective tools to treat and perhaps cure CLL. 2 Introduction B-cell chronic lymphocytic leukemia (CLL) the most common leukemia in the Western hemisphere is characterized by a dynamic imbalance between the proliferation and apoptosis of neoplastic B-lymphocytes co-expressing cluster of differentiation 5 (CD5) and CD19 antigens. Although approximately 20% of CLL patients are diagnosed as a result of routine blood assessments [1] CLL patients may present with a wide range of symptoms typically witnessed in chronic inflammatory diseases. Fatigue for example might at times be so severe that it alone constitutes LDE225 Diphosphate an indication for treatment[2] and disease progression is often associated VCL with constitutional B symptoms such as low-grade fever night sweats and weight loss[2]. A paradoxical deregulation of the immune system that produces an exaggerated inflammatory response to minor insult or to self-antigens coupled with an inadequate response to infectious stimuli is typically found in patients with CLL. The breakdown of tolerance to self-antigens causes a variety of autoimmune phenomena such as autoimmune hemolytic anemia and/or thrombocytopenia (occurring in one third of CLL patients throughout the course of their disease[3]) and overt cutaneous inflammatory reactions. For example more than 50 years ago Weed et al.[4] described delayed hypersensitivity reactions to mosquito bites in patients with CLL and in 1998 Davis et al. described 8 patients with CLL who presented with papulovesicular lesions resembling arthropod bites whose skin biopsies showed T and B lymphocyte and prominent LDE225 Diphosphate eosinophilic infiltrations with eosinophilic granular protein deposition[5]. Although those syndromes are caused by an amplified inflammatory reaction the relatively high rate of infectious complications in CLL patients is the result of an inefficient immune response. Approximately 50% of patients with CLL die of infectious complications[6]. Although most serious complications are therapy related inherent defects in mucosal humeral and cellular immune responses render CLL patients susceptible to contamination[7]. Signs and symptoms of inflammation detected at the onset of the disease worsen with disease progression as is elevated levels of C-reactive protein levels and erythrocyte sedimentation rate [8]. High beta-2 microglobulin (β2M) LDE225 Diphosphate levels usually detected in a broad spectrum of chronic LDE225 Diphosphate inflammatory diseases correlate with disease stage tumor burden and poor prognosis[9]. Whereas high levels of β2M are associated with an increased release of pro-inflammatory cytokines including tumor necrosis factor α (TNF-α) interleukin 1 (IL-1) IL-6 and IL-8 β2M diminishes the ability of dendritic cells to enact a T-cell response[10]. Intracellular pro-inflammatory signaling pathways are activated in CLL cells providing the cells with proliferative and survival advantages and inducing the production of inflammatory cytokines. Novel agents designed to block those pathways induce a dramatic reduction in disease burden and partial restoration of the humeral immune-response in patients with relapsed/refractory disease. We review here the unique features of the inflammatory response in CLL patients and discuss the effects of established and novel anti-inflammatory agents used to treat this disease. 3 The inflammatory response in CLL 3.1 Soluble inflammatory signals The role of cytokines and chemokines in the pathogenesis maintenance and progression of CLL has been the subject of intense research over the past two decades. In LDE225 Diphosphate a recent comprehensive analysis of 23 cytokines in the sera of 84 patients with CLL and 49 age-matched healthy individuals the levels of 17 cytokines mostly.